Rabbit Articular Cartilage Research Articles

Retraction Note: Effects of fibroblast growth factors 2 and low intensity pulsed ultrasound on the repair of knee articular cartilage in rabbits.

The article "Effects of fibroblast growth factors 2 and low intensity pulsed ultrasound on the repair of knee articular cartilage in rabbits" by Z.-F. Tang, H.-Y. Li, published in Eur Rev Med Pharmacol Sci 2018; 22 (8): 2447-2453 - PMID: 29762847 has been retracted by the Editor in Chief. Following some concerns raised on PubPeer (link: https://pubpeer.com/publications/F11DC0DC2B3DAB9753C11C8DC18822), the Editor in Chief has started an investigation to assess the validity of the results as well as possible figure manipulation. The authors have been informed about the journal's investigation but remained unresponsive and have not provided the study's raw data. The journal's investigation identified duplications between Control images A (4 weeks) and E (8 weeks), FHF2 C (4 weeks) and G (8 weeks), and FGF2+LIPU D (4 weeks) and H (8 weeks) of Figure 1. Additionally, duplications were identified between panels A and B of Figure 4. Consequently, the Editor in Chief mistrusts the results presented and has decided to retract the article. This article has been retracted. The Publisher apologizes for any inconvenience this may cause.

Regenerative capacity of morselized cartilage in vitro and in an osteochondral defect model

IntroductionNumerous treatment modalities for focal articular cartilage defects exist, including the use of chondrons from minced cartilage morsels. However, the use of consistent and reproducible morsel sizes to heal these lesions, especially with a recently characterized alginate-Nanocellulose (NC) hydrogel scaffold, has not been investigated. MethodsCartilage was harvested and morselized into 0.5mm, 1.0mm, and 5.0mm diameters, and cultured. Cell viability and chondrogenic gene expression was analyzed. 0.5mm diameter minced cartilage morsels were harvested and used to produce the implant paste. The NC paste was filled into a rabbit articular cartilage defect, and histology was used to assess cartilage repair. ResultsChondrocyte viability of the morsels was highly maintained. Chondrogenic and proliferative genes like ACAN, COL2, COMP, PCNA, SOX9, and PRG4 all increased expression to a varying degree as morsel size decreased. 0.5mm morsels exhibited the highest chondrogenic potential. Also, NC paste containing 0.5mm morsels resulted in complete defect closure unlike marrow stimulation alone. Safranin-O staining demonstrated superior cartilage formation in the defect area. DiscussionSmaller consistent morsel size was found to be linked to increased chondrogenic potential, as hypothesized. However, since PRG4 expression was highest in 1mm morsels and MMP-13 gene expression was significantly decreased in only 0.5mm morsels, this demonstrates the need to adjust morsel size to optimize gene expression of interest. NC paste mixed with 0.5mm morsels produced the greatest regenerative capacity. Exploring the regenerative potential of unique hydrogels and chondron morsel sizes is warranted to provide insight on optimizing clinical implants to improve patient recovery.

Enhancing cartilage regeneration and repair through bioactive and biomechanical modification of 3D acellular dermal matrix.

Acellular dermal matrix (ADM) shows promise for cartilage regeneration and repair. However, an effective decellularization technique that removes cellular components while preserving the extracellular matrix, the transformation of 2D-ADM into a suitable 3D scaffold with porosity and the enhancement of bioactive and biomechanical properties in the 3D-ADM scaffold are yet to be fully addressed. In this study, we present an innovative decellularization method involving 0.125% trypsin and 0.5% SDS and a 1% Triton X-100 solution for preparing ADM and converting 2D-ADM into 3D-ADM scaffolds. These scaffolds exhibit favorable physicochemical properties, exceptional biocompatibility and significant potential for driving cartilage regeneration in vitro and in vivo. To further enhance the cartilage regeneration potential of 3D-ADM scaffolds, we incorporated porcine-derived small intestinal submucosa (SIS) for bioactivity and calcium sulfate hemihydrate (CSH) for biomechanical reinforcement. The resulting 3D-ADM+SIS scaffolds displayed heightened biological activity, while the 3D-ADM+CSH scaffolds notably bolstered biomechanical strength. Both scaffold types showed promise for cartilage regeneration and repair in vitro and in vivo, with considerable improvements observed in repairing cartilage defects within a rabbit articular cartilage model. In summary, this research introduces a versatile 3D-ADM scaffold with customizable bioactive and biomechanical properties, poised to revolutionize the field of cartilage regeneration.

Chondrotoxic effects of tranexamic acid and povidone-iodine on the articular cartilage of rabbits.

To evaluate the chondrotoxic effects of intra-articular use of TXA 20 mg/kg and/or 0.35% PVPI on knee joint cartilage in an experimental model of rabbits. Forty-four male New Zealand adult rabbits were randomly assigned to four groups (control, tranexamic acid (TXA), povidone-iodine (PVPI), and PVPI + TXA). The knee joint cartilage was accessed through an arthrotomy and exposed to physiological saline SF 0.9% (control group), TXA, PVPI, and PVPI followed by TXA. Sixty days after surgical procedure, the animals were sacrificed and osteochondral specimens of the distal femur were obtained. Histological sections of cartilage from this area were stained with hematoxylin/eosin and toluidine blue. The following cartilage parameters were evaluated by the Mankin histological/histochemical grading system: structure, cellularity, glycosaminoglycan content in the extracellular matrix, and integrity of the tidemark. The isolated use of PVPI causes statistically significant changes in cartilage cellularity (p-value = 0.005) and decrease glycosaminoglycan content (p = 0.001), whereas the isolated use of TXA decreased significantly the glycosaminoglycan content (p = 0.031). The sequential use of PVPI + TXA causes more pronounced alterations in the structure (p = 0.039) and cellularity (p = 0.002) and decreased content of glycosaminoglycans (p < 0.001) all with statistical significance. Data suggest that intra-articular use of tranexamic acid 20 mg/kg and intraoperative lavage with 0.35% povidone-iodine solution for three min are toxic to the articular cartilage of the knee in an experimental in vivo study in rabbits.

Mechanism of the inhibitory effect of acupotomy on chondrocyte apoptosis in KOA rabbits explored via proteomics 运用蛋白质组学技术探讨针刀抗KOA兔软骨细胞凋亡的作用机制

ObjectiveTo elucidate the mechanism underlying the inhibitory effect of acupotomy on chondrocyte apoptosis in rabbits with knee osteoarthritis (KOA) through screening, analysis, and verification of apoptosis-related differentially expressed proteins via proteomics. MethodsThirty New Zealand white rabbits were randomly divided into the normal, model, and acupotomy groups, with 10 rabbits in each group. The Vidman method was used to prepare KOA models in the model and acupotomy groups. In the acupotomy group, acupotomy was performed at the midpoints of the patellar ligament and medial and lateral collateral ligaments on the left knees once a week for three weeks. Rabbit articular cartilage protein was quantified in each group, and the proteins with differential expression were profiled via proteomics. The apoptosis-related proteins were further screened, and differentially expressed proteins common among the normal, model, and acupotomy groups were collected for cluster analysis. Pathological changes in chondrocytes were observed via HE staining, and chondrocyte apoptosis was observed under an electron microscope. Quantitative real-time PCR (RT-PCR) and western blot were performed to determine the mRNA and protein expression levels, respectively, of the common apoptosis-related proteins in the three groups. ResultsWestern blot and RT-PCR showed that the protein and mRNA expression levels of TXN, CAP1 and FABP3 were lower (all P < 0.05), whereas that of LTF, SCIN and IL-10 were higher (all P < 0.01) in the acupotomy group than that in the model group. ConclusionThe antiapoptotic effect of acupotomy on chondrocytes in KOA rabbits may be achieved by modulating the protein and mRNA expression of differentially expressed apoptosis-related proteins (TXN, CAP1, FABP3, LTS, SCIN, and IL-10).

A versatile 3D-printable hydrogel for antichondrosarcoma, antibacterial, and tissue repair

• A novel hydrogel with biological activity and photothermal effect was synthesized. • The hydrogel can exert anti-tumor and antibacterial effect through photothermal effect. • The hydrogel can effectively promote the repair of articular cartilage defects in vivo . Following operative treatment of chondrosarcoma, post-surgery tissue reconstruction may be confronted with daunting challenges, including the delayed self-repair of defective tissue, tumor recurrence, and bacterial infection. To overcome these challenges, a methacrylic anhydride (MA) modified sericin (SerMA) solution mixed with procyanidins (PC) loaded polydopamine (PDA) modified ZIF-8 (PC@ZIF-8@PDA) nanoparticles to form a multifunctional PC@ZIF-8@PDA/SerMA hydrogel after exposure under blue light. Hydrogel products with pre-designed shapes were printed out by using the SerMA solution carrying PC@ZIF-8@PDA nanoparticles and chondrocytes, indicating that PC@ZIF-8@PDA/SerMA hydrogels with personalized shapes can be fabricated via 3D printing. Photocrosslinked PC@ZIF-8@PDA/SerMA hydrogel is able to kill chondrosarcoma cells and bacteria, like Staphylococcus aureus (S. aureus) , and Escherichia coli (E. coli) , by its photothermal activity combined with near-infrared radiation (NIR). The PC@ZIF-8@PDA/SerMA hydrogel exhibited an antioxidative activity and a good biocompatibility and was easily monitored by its florescent and photoacoustic properties. Rabbit articular cartilage defects were efficiently repaired by PC@ZIF-8@PDA/SerMA hydrogels with encapsulated corresponding autologous chondrocytes, and mice skin burning wounds were swiftly regenerated by applying this hydrogel. Hence, the PC@ZIF-8@PDA/SerMA hydrogel can be potentially applied to the clinic treatment of chondrosarcoma and tissue defect repair after chondrosarcoma resection due to its multifunction in the future.

Bone marrow stem cells incubated with ellipticine regenerate articular cartilage by attenuating inflammation and cartilage degradation in rabbit model.

Ellipticine (Ellip.) was recently reported to have beneficial effects on the differentiation of adipose-derived stem cells into mature chondrocyte-like cells. On the other hand, no practical results have been derived from the transplantation of bone marrow stem cells (BMSCs) in a rabbit osteoarthritis (OA) model. This study examined whether autologous BMSCs incubated with ellipticine (Ellip.+BMSCs) could regenerate articular cartilage in rabbit OA, a model similar to degenerative arthritis in human beings. A portion of rabbit articular cartilage was surgically removed, and Ellip.+BMSCs were transplanted into the lesion area. After two and four weeks of treatment, the serum levels of proinflammatory cytokines, i.e., tumor necrosis factor α (TNF-α) and prostaglandin E2 (PGE2), were analyzed, while macroscopic and micro-computed tomography (CT) evaluations were conducted to determine the intensity of cartilage degeneration. Furthermore, immuno-blotting was performed to evaluate the mitogen-activated protein kinases, PI3K/Akt, and nuclear factor-κB (NF-κB) signaling in rabbit OA models. Histological staining was used to confirm the change in the pattern of collagen and proteoglycan in the articular cartilage matrix. The transplantation of Ellip.+BMSCs elicited a chondroprotective effect by reducing the inflammatory factors (TNF-α, PGE2) in a time-dependent manner. Macroscopic observations, micro-CT, and histological staining revealed articular cartilage regeneration with the downregulation of matrix-metallo proteinases (MMPs), preventing articular cartilage degradation. Furthermore, histological observations confirmed a significant boost in the production of chondrocytes, collagen, and proteoglycan compared to the control group. Western blotting data revealed the downregulation of the p38, PI3K-Akt, and NF-κB inflammatory pathways to attenuate inflammation. The transplantation of Ellip.+BMSCs normalized the OA condition by boosting the recovery of degenerated articular cartilage and inhibiting the catabolic signaling pathway.

Warm acupuncture stimulation improves cartilage damage and motor function by regulating JAK2/STAT3 signaling pathway in rabbits with knee osteoarthritis

To observe the effect of warm acupuncture on the expression of Janus protein tyrosine kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway and inflammatory factors of articular cartilage in rabbits with knee osteoarthritis (KOA), so as to explore its underlying mechanisms in improving KOA. New Zea-land rabbits were randomly divided into blank, model, warm acupuncture and medication groups (12 rabbits in each group). The KOA model was prepared by using the right hind limb tubular plaster extension fixation method. The rabbits in the warm acupuncture group received acupuncture of "Neixiyan"(EX-LE4),"Waixiyan"(ST35),"Heding"(EX-LE2) and "Zusanli"(ST36), followed by attaching an ignited moxa-stick segment to the acupuncture-handle. The treatment was conducted for 15 min, once a week for 4 weeks. The rabbits in the medication group received gavage of diclofenac sodium solution(0.35 mg/kg), once daily for 4 weeks. The dysfunction severity state of the rabbit's knee-joint was evaluated using Lequesne scale (0-3 points), and the histopathological changes of cartilage were observed under microscope after H.E. staining and the state of distribution of chondrocytes in different layers and the extracellular matrix was assessed using Mankin score (0-6 points). The contents of serum interleukin (IL)-6, tumor necrosis factor-α (TNF-α) and matrix metalloproteinase-9 (MMP-9) were measured by using ELISA, and the expression levels of p-JAK2/JAK2, p-STAT3/STAT3 and MMP-9 in knee cartilage tissue were detected using Western blot. Compared with the blank group, the Lequesne score, Mankin score, and the contents of serum IL-6, TNF-α and MMP-9, and the ratios of p-JAK2/JAK2 and p-STAT3/STAT3, and the expression level of MMP-9 protein in knee cartilage tissue were significantly increased in the model group (P<0.01). In comparison with the model group, the Lequesne score, Mankin score, contents of serum IL-6, TNF-α and MMP-9, and the ratios of p-JAK2/JAK2 and p-STAT3/STAT3, and the expression of MMP-9 protein in knee cartilage tissue were notably decreased in both the warm acupuncture and medication groups (P<0.01,P<0.05). The levels of Lequesne score, Mankin score, contents of serum IL-6, TNF-α and MMP-9, and the ratios of p-JAK2/JAK2 and p-STAT3/STAT3 in knee cartilage tissue were significantly lower in the warm acupuncture group than in the medication group (P<0.01, P<0.05). No significant difference was found between the warm acupuncture and medication groups in the expression of MMP-9 protein (P>0.05). Outcomes of H.E. showed injury of the perichondrium of knee joint, obvious reduction of the cartilage matrix staining, cystic changes, clustered and disordered arrangement and severe pyknosis and necrosis of the surface cells with reduction of number of cells and increase of vacuoles in the model group, which was milder in both warm acupuncture and medication groups. Warm acupuncture can improve motor function and reduce cartilage injury in KOA rabbits, which may be related to its functions in inhibiting the secretion of pro-inflammatory factors and regulating JAK2/STAT3 signaling and downregulating MMP-9 expression in the cartilage tissue.

Subversive molecular role of Krüppel-like factor 5 in extracellular matrix degradation and chondrocyte dedifferentiation.

Osteoarthritis (OA) is the most common joint disorder worldwide and a leading cause of pain and disability. However, the pathogenesis of osteoarthritis has not been elucidated. Krüppel-like factor (KLF)-5 is involved in several biological processes, including inflammation and cell differentiation, but its role in OA has not been evaluated. In this study, we investigated the role of KLF-5 in chondrocyte differentiation. KLF-5 overexpression in chondrocytes induced a loss of type II collagen expression and sulfated proteoglycan synthesis at the transcriptional and translational levels. Based on immunofluorescence staining, the ectopic expression of KLF-5 reduced type II collagen expression. In contrast, with KLF-5-transfected cells, KLF-5 siRNA transfection-induced type II expression also blocked dedifferentiation caused by the overexpression of KLF-5. In zebra fish, KLF-5 reduced the sulfated proteoglycan synthesis of ceratobranchial cartilage. Our results suggest that KLF-5 plays a pivotal role in the dedifferentiation of rabbit articular cartilage and zebra fish, providing a basis for therapeutic strategy for osteoarthritis aimed at controlling cartilage destruction.

Chondroitin sulfate cross-linked three-dimensional tailored electrospun scaffolds for cartilage regeneration

Degenerated cartilage tissues remain a burgeoning issue to be tackled, while bioactive engineering products available for optimal cartilage regeneration are scarce. In the present study, two-dimensional (2DS) poly(l-lactide-co-ε-caprolactone)/silk fibroin (PLCL/SF)-based scaffolds were fabricated by conjugate electrospinning method, which were then cross-linked with chondroitin sulfate (CS) to further enhance their mechanical and biological performance. Afterwards, three-dimensional (3D) PLCL/SF scaffolds (3DS) and CS-crosslinked 3D scaffolds (3DCSS) with tailored size were successfully fabricated by an in-situ gas foaming in a confined mold followed by freeze-dried. Gas-foamed scaffolds displayed high porosity, rapid water uptake, and stable mechanical properties. While all of the scaffolds exhibited good cytocompatibility in vitro; 3DCSS showed better cell seeding efficiency and chondro-protective effect compared to other scaffolds. Besides, 3DCSS scaffolds supported the formation of more mature cartilage-like tissues along with the best repair outcome in a rabbit articular cartilage defect model in vivo, as well as less expression level of pro-inflammatory cytokines, including interleukin (IL)-1β and tumor necrosis factor (TNF)-α than that of the other groups. Taken together, 3DCSS may provide an alternative therapeutic option for cartilage tissue repair.

RNA isolation from micro-quantity of articular cartilage for quantitative gene expression by microarray analysis.

Isolation of quality RNA from articular cartilage has been challenging due to low cellularity and the high abundance of extracellular matrix and proteoglycan proteins. Recently developed methods for isolation of high quality RNA from cartilage are more applicable to larger cartilage specimens typically weighing at least 25 mg. While these methods generate RNA suitable for analysis, they are less successful with smaller tissue inputs. For the study of small focal defect cartilage specimens an improved RNA extraction method is needed. Here we report a protocol for direct RNA isolation from less than 3 mg of wet weight rabbit articular cartilage for quantitative microarray gene profiling. This protocol is useful for identifying differentially expressed genes in chondrocytes following focal cartilage repair and can potentially be adopted for gene expression analysis of cartilage biopsy specimens from human joints.

Analysing the Role of Platelet Rich Plasma As Biological Stimulator for Cartilage Regeneration: An Experimental Study

Background: In articular cartilage defects and degenerative cartilage lesions, platelet-rich plasma(PRP) is increasingly used. PRP is an autologous concentration of platelets containing a high number of factors which are responsible for growth. In the healing, recovery and acceleration of biochemical processes, these growth factors play a role in reducing the pain associated with joint injuries. The latest world research shows excellent results in reducing pain by using PRP and it has tremendous scope in reducing the knee pain as well as in regeneration of the articular cartilage. This study aims to analyse the effectiveness of Autologous PRP as biologic stimulator for Cartilage Regeneration in Rabbit Model.&#x0D; Method: This will be a prospective experimental study carried out on 10 rabbits at Animal House in JNMC, Wardha. Osteoarthritis will be induced in the rabbits by destruction of articular cartilage. Then platelet rich plasma therapy. Will be given to induce the regeneration of the cartilage.&#x0D; Expected Results: Evidence of regeneration of articular cartilage in rabbits with osteoarthritis through Platelet Rich Plasma Therapy.

The use of a novel deer antler decellularized cartilage-derived matrix scaffold for repair of osteochondral defects

BackgroundThe physiologic regenerative capacity of cartilage is severely limited. Current studies on the repair of osteochondral defects (OCDs) have mainly focused on the regeneration of cartilage tissues. The antler cartilage is a unique regenerative cartilage that has the potential for cartilage repair.MethodsAntler decellularized cartilage-derived matrix scaffolds (adCDMs) were prepared by combining freezing-thawing and enzymatic degradation. Their DNA, glycosaminoglycans (GAGs), and collagen content were then detected. Biosafety and biocompatibility were evaluated by pyrogen detection, hemolysis analysis, cytotoxicity evaluation, and subcutaneous implantation experiments. adCDMs were implanted into rabbit articular cartilage defects for 2 months to evaluate their therapeutic effects.ResultsAdCDMs were observed to be rich in collagen and GAGs and devoid of cells. AdCDMs were also determined to have good biosafety and biocompatibility. Both four- and eight-week treatments of OCDs showed a flat and smooth surface of the healing cartilage at the adCDMs filled site. The international cartilage repair society scores (ICRS) of adCDMs were significantly higher than those of controls (porcine dCDMs and normal saline) (p < 0.05). The repaired tissue in the adCDM group was fibrotic with high collagen, specifically, type II collagen.ConclusionsWe concluded that adCDMs could achieve excellent cartilage regeneration repair in a rabbit knee OCDs model. Our study stresses the importance and benefits of adCDMs in bone formation and overall anatomical reconstitution, and it provides a novel source for developing cartilage-regenerating repair materials.

Comparison between Intra-Articular Injection of Infrapatellar Fat Pad (IPFP) Cell Concentrates and IPFP-Mesenchymal Stem Cells (MSCs) for Cartilage Defect Repair of the Knee Joint in Rabbits.

Mesenchymal stem cells (MSCs) have emerged as a promising therapeutic method in regenerative medicine. Our previous research adopted a simple nonenzymatic strategy for the preparation of a new type of ready-to-use infrapatellar fat pad (IPFP) cell concentrates. The aim of this study was to compare the therapeutic efficacy of intra-articular (IA) injection of autologous IPFP cell concentrates and allogeneic IPFP-MSCs obtained from these concentrates in a rabbit articular cartilage defect model. IPFP-MSCs sprouting from the IPFP cell concentrates were characterized via flow cytometry as well as based on their potential for differentiation into adipocytes, osteoblasts, and chondrocytes. In the rabbit model, cartilage defects were created on the trochlear groove, followed by treatment with IPFP cell concentrates, IPFP-MSCs, or normal saline IA injection. Distal femur samples were evaluated at 6 and 12 weeks posttreatment via macroscopic observation and histological assessment based on the International Cartilage Repair Society (ICRS) macroscopic scoring system as well as the ICRS visual histological assessment scale. The macroscopic score and histological score were significantly higher in the IPFP-MSC group compared to the IPFP cell concentrate group at 12 weeks. Further, both treatment groups had higher scores compared to the normal saline group. In comparison to the latter, the groups treated with IPFP-MSCs and IPFP cell concentrates showed considerably better cartilage regeneration. Overall, IPFP-MSCs represent an effective therapeutic strategy for stimulating articular cartilage regeneration. Further, due to the simple, cost-effective, nonenzymatic, and safe preparation process, IPFP cell concentrates may represent an effective alternative to stem cell-based therapy in the clinic.

Effects of Androgen Receptor Overexpression on Chondrogenic Ability of Rabbit Articular Chondrocytes.

The role of sex hormones and their receptors has drawn much attention in the process of cartilage regeneration. This study aimed to investigate the effect of androgen receptor (AR) on the chondrogenic ability of articular chondrocytes and the related mechanism. Articular chondrocytes were isolated, cultured, identified by toluidine blue staining and then transduced with lentivirus carrying the AR gene. The cell viability was determined using Cell Counting Kit-8, and cell apoptosis was assessed by flow cytometry analysis. The effects of AR overexpression on the expression of cartilage-specific proteins and some signalling molecules were evaluated by real-time PCR and Western blotting. Using 24 New Zealand rabbits, the regeneration of rabbit articular cartilage defects was further investigated in vivo and evaluated histologically. The overexpression of AR significantly reduced the apoptosis rate of chondrocytes but did not affect their proliferation. The overexpression of AR also promoted the expression of Sry-related HMG box 9, collagen II and aggrecan, decreased the expression of matrix metalloproteinase-13, and downregulated p-S6 and RICTOR. The experimental group with AR-overexpressing chondrocytes exhibited superior regeneration of cartilage defects. AR overexpression can maintain the phenotype of chondrocytes and promote chondrogenesis in vitro and in vivo. mTOR-related signalling was inhibited.

Effects of in vitro low oxygen tension preconditioning of buccal fat pad stem cells on in Vivo articular cartilage tissue repair

AimsProgenitor cells-based regenerative strategy has shown promise to repair cartilage, an avascular tissue in which cells experience hypoxia. Hypoxia is known to improve the early chondrogenic differentiation of stem cells. Therefore, this study aimed to determine whether hypoxia preconditioning could be used to enhance the regenerative potential of the combination of buccal fat pad stem cells (BFPSCs) and bilayer chitosan-based hydrogel scaffold for articular cartilage repair. Materials and methodsHuman BFPSCs were seeded on the bilayer chitosan-based hydrogel scaffolds in the culture medium. The viability and proliferation of cells on the scaffolds were monitored using scanning electron microscopy (SEM), MTT assay, and DAPI staining. Hypoxia preconditioned BFPSCs-seeded scaffolds were transplanted into rabbit articular cartilage knee defects for 12 weeks. The newly formed tissue was evaluated by cartilage-specific immunohistological analysis and histological staining. Key findingsIt was found that the chondrogenic differentiation and osteochondral conjunction in articular cartilage defect via BFPSCs-seeded bilayer scaffolds was enhanced by hypoxic preconditioning compared to a normoxic environment. SignificanceBased on our study, the integrity with subchondral bone in osteochondral defect was enhanced by BFPSCs on bilayer scaffold. Thus, this study provides evidence on the design of preconditioned cell-seeded bilayer hydrogels for articular cartilage regeneration.

Chondroprotective effect of Alpinia oxyphylla extract in experimentally induced cartilage degradation in rabbit articular cartilage explants.

Alpinia oxyphylla is a widely used medicinal herb for diarrhea, gastralgia, tumors, hypertention, and cerebrovascular disorders. Here, we evaluated the chondroprotective effect of A.oxyphylla dried fruit ethanol extract (AOE) against cartilage degradation in rabbit articular cartilage explants. Treatment of interleukin-1α (IL-1α) and plasminogen increased degraded collagen release in culture supernatants, but pretreatment of AOE (50, 100, 200µg/ml) inhibited the collagen release in dose-dependent manner. To examine the mechanism of action of AOE on chondroprotection, the level of matrix metalloproteinases-3 (MMP-3), matrix metalloproteinases-13 (MMP-13), tissue inhibitor of metalloprotease-1 (TIMP-1), and inflammatory mediators like prostaglandin E2 (PGE2 ) and nitric oxide (NO) was evaluated. AOE inhibited upregulation of MMP-3 and MMP-13 and downregulation of TIMP-1 and also reduced increase of PGE2 and NO level induced by exposure of IL-1α and plasminogen. These results indicate that AOE show chondroprotective effect through inhibiting collagen degradation via regulating MMPs, TIMP-1, and inflammatory mediators. PRACTICAL APPLICATIONS: Osteoarthritis (OA) is a one of the most common chronic disorders in elderly persons. Because the regenerative power of joint articular cartilage is very low, treatment of OA is difficult to expect complete recovery. Therefore, there is a need to develop a therapeutic agent that can safely and effectively inhibit the cartilage destruction. For the first time, we exhibited the inhibitory effect of AOE on collagen degradation through regulating MMPs and TIMP-1 in articular cartilage explants. These findings support AOE could be used as herbal therapeutic application for protecting articular cartilage to prevent OA.

Hyaluronic Acid Supplement as a Chondrogenic Adjuvant in Promoting the Therapeutic Efficacy of Stem Cell Therapy in Cartilage Healing.

The main aim of this study is to investigate the therapeutic efficacy of direct intra-articular injection of bone-marrow-derived stem/stromal cells (BMSCs) and the adjuvant role of hyaluronic acid (HA) in facilitating rabbit articular cartilage repair. First, rabbit BMSCs were treated with a medium containing different concentrations of HA. Later, HA’s influence on BMSCs’ CD44 expression, cell viability, extracellular glycosaminoglycan (GAG) synthesis, and chondrogenic gene expression was evaluated during seven-day cultivation. For the in vivo experiment, 24 rabbits were used for animal experiments and 6 rabbits were randomly allocated to each group. Briefly, chondral defects were created at the medial femoral condyle; group 1 was left untreated, group 2 was injected with HA, group 3 was transplanted with 3 × 106 BMSCs, and group 4 was transplanted with 3 × 106 BMSCs suspended in HA. Twelve weeks post-treatment, the repair outcome in each group was assessed and compared both macroscopically and microscopically. Results showed that HA treatment can promote cellular CD44 expression. However, the proliferation rate of BMSCs was downregulated when treated with 1 mg/mL (3.26 ± 0.03, p = 0.0002) and 2 mg/mL (2.61 ± 0.04, p = 0.0001) of HA compared to the control group (3.49 ± 0.05). In contrast, 2 mg/mL (2.86 ± 0.3) of HA treatment successfully promoted normalized GAG expression compared to the control group (1.88 ± 0.06) (p = 0.0009). The type II collagen gene expression of cultured BMSCs was significantly higher in BMSCs treated with 2 mg/mL of HA (p = 0.0077). In the in vivo experiment, chondral defects treated with combined BMSC and HA injection demonstrated better healing outcomes than BMSC or HA treatment alone in terms of gross grading and histological scores. In conclusion, this study helps delineate the role of HA as a chondrogenic adjuvant in augmenting the effectiveness of stem-cell-based injection therapy for in vivo cartilage repair. From a translational perspective, the combination of HA and BMSCs is a convenient, ready-to-use, and effective formulation that can improve the therapeutic efficacy of stem-cell-based therapies.

Post-Adipose-Derived Stem Cells (ADSC) Stimulated by Collagen Type V (Col V) Mitigate the Progression of Osteoarthritic Rabbit Articular Cartilage.

Collagen is essential for cartilage adhesion and formation. In the present study, histology, immunofluorescence, morphometry, and qRT-PCR suggested that adipose-derived stem cells (ADSCs) stimulated by type V collagen (Col V) induce a significant increase of type II collagen (Col II) in the degenerative area of surgical-induced osteoarthritic rabbit articular cartilage (OA). In vitro, the effects of Col V on the proliferation and differentiation of ADSC were investigated. The expression of the cartilage-related genes Col2a1 and Acan was significantly upregulated and Pou5fl was downregulated post-ADSC/Col V treatment. Post-ADSC/Col V treatment, in vivo analyses revealed that rabbits showed typical signs of osteoarthritic articular cartilage regeneration by hematoxylin and eosin (H&E) and Safranin O/Fast Green staining. Immunohistochemical staining demonstrated that the volume of Col II fibers and the expression of Col II protein were significantly increased, and apoptosis Fas ligand positive significantly decreased post-ADSC/Col V treatment. In conclusion, the expression of Col II was higher in rabbits with surgical-induced osteoarthritic articular cartilage; hence, ADSC/Col V may be a promising therapeutic target for OA treatment.

Study on specific proteins involved in articular cartilage regeneration activity induced by decalcified bone transplantation.

BackgroundThrough a comprehensive analysis of the joint synovial fluid produced in the process of rabbit articular cartilage regeneration, the role and characteristics of knee synovial fluid in the process of decalcified bone transplantation-induced articular cartilage regeneration were explored.MethodsTwenty New Zealand white rabbits (approximately 2.5 kg in weight) were selected, and bilateral distal femoral bones from two randomly selected rabbits were extracted. After decalcification, the bones were cut into 2 mm × 4 cm long decalcified bone strips. Meanwhile, the other 18 rabbits were randomly divided into three groups: the test group (8 rabbits), the positive control group (6 rabbits), and the blank group (4 rabbits). In the test group, the decalcified bone joint was transplanted into the rabbits at the articular cartilage defect; in the positive control group, the articular cartilage defect of the rabbits were treated and put aside; in the blank group, no rabbits were treated. On the day of transplantation, and on the 4th, 8th, 12th, and 16th weeks after transplantation, the joint synovial fluid of each group was taken for two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF-MS) analysis, and related database verification and identification, and compared with the positive control group and the blank group.ResultsUsing 2D-PAGE to separate various proteins in the synovial fluid of the rabbit knee joints, it was found that there were differential protein spots in the test group compared with the blank group and the positive control group. After conducting a comparative search and query in the UniProt database, through comprehensive analysis, it was finally found that three proteins with molecular weights of 23,429.4, 57,431.4, and 26,071.1 that may be related to the regeneration of articular cartilage appeared in the test group.ConclusionsIn the process of inducing the regeneration of articular cartilage using decalcified bone transplantation, knee joint synovial fluid produced specific proteins, which may play an important role in the regeneration of articular cartilage. These findings may offer novel ideas in laying a foundation for the in-depth study of articular cartilage regeneration.